John Deere manufactures a Max Emerge Drawn Conservation Flex-fold planter. The heart of the John Deere planter is a metering unit which retains a circular rotatable seed disk that separates the interior of the metering unit into two chambers, one on each side of the disk. The seed disks employed in the machine have a plurality of holes, with the centers thereof spaced to define a circle having a radius a little less than the radius of the disk. A vacuum is drawn in the chamber formed on one side of the disk and seeds are introduced into the chamber on the opposite side of the disk. The diameter of the holes in the seed disks are sized such that, when operating properly, the vacuum will draw one seed against the aperture of each hole in the disk and retain the seed as the disk rotates to a position above a seed tube, at which point the disk moves away from the vacuum chamber and the seed falls away from the disk and into the seed tube to be planted.
The planter is intended for use with many types of seed, including sunflower, cotton, soybean, sorghum, sugar beets, popcorn, sweet corn, and corn seed (feed corn seed). Each type of seed has a different size and configuration and the planter is, therefore, provided with a plurality of seed disks, which each of the seed disks having a different configuration of holes through which the vacuum is drawn to move seeds from the input to the seed tube.
The manual for the 7200 Max Emerge, 16 row, narrow flex-fold planter, for example, describes and depicts thirteen different seed disks. According to the manual, the seed size for certain grains, such as corn seed, vary widely. The manual recommends disk H136478 for the smallest sized corn seed, recommends disk A43215 for medium sized corn seed, and recommends disk A50617 for large sized corn seed.
The proper operation of the John Deere planter, therefore, requires the selection of the appropriate seed disk for use with the size and type of seed to be planted. To compensate for differences in weight, size, and shape of the various seeds, the proper operation of the planter also requires adjustments to the vacuum drawn to one side of the seed disk and depending on the size of seed being planted, the installation or removal of certain optional features. It is also recommended that the machine be monitored during its use and that the strength of the vacuum be adjusted if the machine is found to be under planting or over planting seed.
The machine scratches a trough in the ground and when the machine is operating properly it will deposit one seed every six inches along the trough or one hundred seeds along a six hundred inch length of ground. When the one hundred seeds are all equally spaced from one another, the stalks of corn, or other produce that grows from the seed, will not interfere with each other and the harvest from a tract of land will be maximized. When the machine drops two seeds at once through the seed tube the stalks that grow from the two seeds compete for the same nutrients from the ground and the same light from the sun resulting in both stalks being stunted and a reduced harvest from the tract of land. Similarly, when the machine fails altogether to drop a seed at one of the planting locations, the harvest is also reduced. A machine is considered to be operating at one hundred percent efficiency if it will plant one hundred seeds in one hundred equally spaced planting locations along a length of ground. Where the machine plants ninety-eight seeds in one hundred locations, it is considered to be operating at ninety-eight percent efficiency and where it is planting one hundred and two seeds in every one hundred locations (a second seed into each of two locations), the machine is considered to be operating at one hundred and two percent efficiency. A farmer will consider a machine that is operating outside the range of ninety-five percent to one hundred and five percent to be unacceptably inefficient and in either case will be required to adjust the vacuum or replace the seed disks of the machine to improve its efficiency. The desired operating range for such machines is between ninety-nine percent and one hundred and one percent efficiency. The planters manufactured by John Deere are adapted to plant from four to thirty-one rows simultaneously with a metering unit including a hopper retaining seed and a seed disk for each row to be planted by the machine.
The difficulties of maintaining proper efficiency are accentuated in the case of corn seed, which is one of the major grains for which the John Deere planter is employed. Although it would be desirable for a farmer to obtain seed which is of all the same size, as a practical matter, he must deal with seeds of varying size. As previously stated, John Deere offers three different seed disks for use in planting corn seed, one disk for each of three ranges of seed size.
In my patent application filed Mar. 28, 2002, now U.S. Pat. No. 6,932,236 B2, I disclosed a kit that includes an improved seed disk for insertion into the metering unit of a John Deere planter to improve the efficiency with which seed, especially corn seed, is planted. Specifically, machines having metering units fitted with the parts described in my patent no. 6,932,236 B1 will reliably deposit between ninety-nine and one hundred and one corn seeds along a length of ground that should receive one hundred seeds.
Another factor that effects the harvest produced by a tract of land is the spacing between the seeds along a row. Even though a row of seeds may have the correct number of seeds spaced along its length, if the seeds are not equally spaced apart from each other, the seeds that are spaced too close together will experience the problems of crowding and seeds that are spaced too far apart will not flourish enough to compensate for the stalks that are crowded.
Farmers have long recognized that John Deere planters have difficulty maintaining the spacing between seeds needed to maximize the harvest for a tract of land. The recognized solution to improve spacing is to operate the planter at a slower rate of speed. Although John Deere recommends that its planter be pulled at five miles per hour, farmers who want to avoid having a harvest that is reduced by poor seed spacing will choose to pull their planters at four miles per hour. Reducing the speed at which the planter is pulled increases the time required for planting and farmers who plant large acreage often encounter weather conditions and the like that allow a short planning season. In such cases, the farmer may be forced to pull the planter at six miles per hour, causing the spacings of the seeds to be even more uneven than when pulled at five miles per hour.
Even planters having metering units fitted with parts in accordance with my U.S. Pat. No. 6,932,236 B1 experience uneven spacing between seeds. This problem has been partially dealt with in my co-pending application Ser. No. 10/803,265 filed Mar. 18, 2004, but that has not resulted in a total solution the problem. It would be desirable; therefore, to provide an improvement to a vacuum seed planter that would improve the spacings between seeds planted without requiring that the machine be pulled at a slower rate of speed.